Probe card assembly

ABSTRACT

Disclosed is a probe card assembly including a main body, a probe base provided at a center of the main body, and a plurality of test probes connecting the main body and the probe base. Therein, each of the test probes has a tip extending out from the probe base for contacting and testing a wafer. The test probes include at least one power probe, at least one grounding probe and a plurality of signal probes, wherein each of the test probes has a middle section between the main body and the probe base. Each of the power probe and the signal probes further contains therein a core that is wrapped by an insulation layer.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a probe card assembly and, moreparticularly, to a probe card assembly for testing semiconductor wafers.

2. Description of Related Art

In a process for manufacturing semiconductor wafers, test equipments andprobe cards are typically used for testing dies on the wafers. Someprior arts, such as U.S. Pat. Nos. 7,053,638, 6,515,358, 6,137,297,5,670,889, 7,271,603, 7,304,488 and 6,478,596, have proposed relatedapproaches. A probe card has precise contacting means for contacting andelectrifying each die on a wafer to test the dies and thereby ensurethat the wafer is fabricated with electrical properties and performancesanswering to its design specifications. In recent years, the developmentof test equipments and probe cards tends toward high-frequencyproperties to adapt to the emerging semiconductor apparatuses capable ofhigh-speed operation. However, when a traditional cantilever probe cardhaving closely arranged test probes is used in high-frequency tests,noises brought by electromagnetic interference between the probes cansignificantly affect the consistency of test results and additionalrepeated tests may be required, resulting in reduced productivity andtesting efficiency. Hence, a need exists for a structural improvement inthe traditional probe card to remedy the problem of the prior arts.

SUMMARY OF THE INVENTION

In an attempt to overcome the defects of the prior arts, the presentinvention provides a probe card assembly and test probes used therein.The probe card assembly comprises a main body, a probe base provided ata center of the main body, and a plurality of test probes connecting themain body and the probe base. Therein, each of the test probes has a tipextending out from the probe base for contacting and testing a wafer.The test probes comprise at least one power probe, at least onegrounding probe and a plurality of signal probes, wherein each of thetest probes has a middle section between the main body and the probebase. Each of the power probe and the signal probes further containstherein a core that is wrapped by an insulation layer. The groundingprobe is a bare probe with its middle section coated with a conductiveadhesive that extends to a grounding end of the main body of the probecard assembly. At least one of the signal probes or the power probe alsohas its middle section coated with the conductive adhesive, which alsoextends to the grounding end of the main body of the probe cardassembly. Thereby, the probe card assembly is enabled to transmithigh-frequency signals smoothly.

Thus, a main objective of the present invention is to provide a probecard assembly for testing wafers with enhanced accuracy inhigh-frequency tests.

Another objective of the present invention is to provide a probe cardassembly for testing wafers with significantly reduced noises duringhigh-frequency tests.

An additional objective of the present invention is to provide a probecard assembly for testing wafers, wherein inductance between a powerprobe and a grounding probe of the probe card assembly can beeffectively reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention as well as a preferred mode of use, further objectives andadvantages thereof will best be understood by reference to the followingdetailed description of illustrative embodiments when read inconjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic drawing of a probe card assembly according to afirst preferred embodiment of the present invention;

FIG. 2 is a partial, cross-sectional view of the probe card assemblyaccording to the first preferred embodiment of the present invention;

FIG. 3 is a cross-sectional view of a signal probe of the probe cardassembly according to the first preferred embodiment of the presentinvention; and

FIG. 4 is a cross-sectional view of a grounding probe of the probe cardassembly according to the first preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a probe card assembly for probing awafer. Since the operational principles and basic functions of the probecard assembly are well known to people of ordinary skill in the art, adetailed description of such principles and functions will be omittedherein. Meantime, the accompanying drawings to which the followingdescription refers are intended to illustrate structural features of thepresent invention only schematically and therefore are not, and need notbe, drawn to scale.

Please refer to FIGS. 1 through 4 for a probe card assembly 100according to a first preferred embodiment of the present invention. Theprobe card assembly 100 primarily comprises a main body 1, a probe base2 provided at a center of the main body 1, and a plurality of testprobes 3 connecting the main body 1 and the probe base 2. The testprobes 3 comprise at least one power probe 32, at least one groundingprobe 33 and a plurality of signal probes 34. Each of the test probes 3has a middle section M between the main body 1 and the probe base 2.Each of the test probes 3 further has a tip 31 extending out from theprobe base 2 for contacting a wafer (not shown) and testing electricalproperties thereof. Besides, each of the power probe 32 and the signalprobes 34 further contains therein a core 35 that is wrapped by aninsulation layer 4, whereas the grounding probe 33 is a bare probewithout the insulation layer 4.

In view that the closely arranged test probes 3 tend to suffer frommutual signal interference or excessive inductance, according to thepresent embodiment of the present invention, the middle sections M ofthe grounding probe 33 and of the signal probes 34 are coated with aconductive adhesive 5 that extends to a grounding end of the main body1. The grounding end may further connect with a grounding layer in a PCBof the main body 1. FIG. 3 shows a cross-sectional view of one saidsignal probe 34, wherein the conductive adhesive 5 is applied to anouter surface of the insulation layer 4. FIG. 4 shows a cross-sectionalview of the grounding probe 33, wherein the conductive adhesive 5 isapplied to the core 35 of the bare probe. Thereupon, relatedhigh-frequency noises can be led to the grounding probe 33 and thegrounding end via the conductive adhesive 5, so as to reduce inductance.Furthermore, as signals on the signal probes 34 are secured from lossand interference, the signal probes 34 are enabled to transmithigh-frequency signals smoothly and perform high-frequency testssuccessfully. In addition, since signal interference is mostlyattributed to high-frequency noises, the signal probes 34 in the presentembodiment may be high-frequency signal probes (not shown). It is alsonoted that the conductive adhesive 5 functions better when coated on thehigh-frequency signal probes than on the normal signal probes 34.

According to a second preferred embodiment of the present invention, aprobe card assembly 100 primarily comprises a main body 1, a probe base2 provided at a center of the main body 1, and a plurality of testprobes 3 connecting the main body 1 and the probe base 2. Unlike thefirst preferred embodiment, a conductive adhesive 5 in the presentembodiment is applied to outer surfaces of middle sections M of thegrounding probe 33 and of the power probe 32, and extends to a groundingend of the main body 1 so as to substantially reduce inductance betweenthe power probe 32 and the grounding probe 33. Thereupon, relatedhigh-frequency noises can be led to the grounding probe 33 and thegrounding end via the conductive adhesive 5 so that signals on thesignal probes 34 are secured from loss and interference. Consequently,the signal probes 34 are enabled to transmit high-frequency signalssmoothly and perform successful high-frequency tests. Othercharacteristics of the probe card assembly 100 of the present embodimentare similar to those disclosed in the first preferred embodiment.

According to a third preferred embodiment of the present invention, aprobe card assembly 100 primarily comprises a main body 1, a probe base2 provided at a center of the main body 1, and a plurality of testprobes 3 connecting the main body 1 and the probe base 2. Unlike thefirst and the second preferred embodiments, all the power probe 32,grounding probe 33 and signal probes 34 in the present embodiment haveouter surfaces of their middle sections M coated with a conductiveadhesive 5 that extends to a grounding end of the main body 1 to achievebetter results.

The present invention has been described with reference to preferredembodiments thereof and it is understood that the embodiments are notintended to limit the scope of the present invention. Moreover, as thecontents disclosed herein should be readily understood and can beimplemented by a person skilled in the art, all equivalent changes ormodifications which do not depart from the spirit of the presentinvention should be encompassed by the appended claims.

1. A probe card assembly, comprising a main body, a probe base providedat a center of the main body, and a plurality of test probes connectingthe main body and the probe base, wherein each of the test probes has atip extending out from the probe base for contacting a wafer to betested, and the test probes comprise at least one power probe, at leastone grounding probe and a plurality of signal probes, in which each ofthe test probes has a middle section between the main body and the probebase, the probe card assembly being characterized in that: the middlesections of at least one said grounding probe and at least one saidsignal probe have outer surfaces thereof coated with a conductiveadhesive that extends to a grounding end of the main body of the probecard assembly, wherein the grounding probe is a bare probe without aninsulation layer and each of the signal probes contains therein a corethat is wrapped by an insulation layer.
 2. The probe card assembly asclaimed in claim 1, wherein the signal probe whose middle section iscoated on the outer surface thereof with the conductive adhesive is ahigh-frequency signal probe.
 3. A probe card assembly, comprising a mainbody, a probe base provided at a center of the main body, and aplurality of test probes connecting the main body and the probe base,wherein each of the test probes has a tip extending out from the probebase for contacting a wafer to be tested, and the test probes compriseat least one power probe, at least one grounding probe and a pluralityof signal probes, in which each of the test probes has a middle sectionbetween the main body and the probe base, the probe card assembly beingcharacterized in that: the middle sections of at least one saidgrounding probe and at least one said power probe have outer surfacesthereof coated with a conductive adhesive that extends to a groundingend of the main body of the probe card assembly, wherein the groundingprobe is a bare probe and the power probe contains therein a core thatis wrapped by an insulation layer.
 4. A probe card assembly, comprisinga main body, a probe base provided at a center of the main body, and aplurality of test probes connecting the main body and the probe base,wherein each of the test probes has a tip extending out from the probebase for contacting a wafer to be tested, and the test probes compriseat least one power probe, at least one grounding probe and a pluralityof signal probes, in which each of the test probes has a middle sectionbetween the main body and the probe base, the probe card assembly beingcharacterized in that: the middle sections of at least one saidgrounding probe and the test probes other than the grounding probe haveouter surfaces thereof coated with a conductive adhesive that extends toa grounding end of the main body of the probe card assembly, wherein thegrounding probe is a bare probe and each of the test probes other thanthe grounding probe contains therein a core that is wrapped by aninsulation layer.